Implantable medical systems, for example, those providing electrical stimulation for cardiac or neurological therapy, often include a pulse generator device and an elongate medical electrical lead that extends from the device to a stimulation site in a body of a patient. Numerous configurations of implantable medical electrical lead connectors have been disclosed over the years, many of which are directed toward compliance with international industry standards; these standards specify essential dimensions and performance requirements to assure compatibility of connection between pulse generator device connector receptacles and lead connectors among a variety of manufacturers. One such standard dictates the form for a four-pole in-line connector of cardiac pacing and defibrillation leads and is commonly known as the IS-4 or DF-4 standard.
FIG. 1A is a plan view of an exemplary implantable medical electrical lead 100, which includes a connector assembly 120 and a terminal connector pin 110 that protrudes proximally from a proximal end 121 of assembly 120 to form an in-line connector in conformance with the aforementioned DF-4 standard. FIG. 1A illustrates lead 100 including a low voltage distal-most electrode lde, a first high voltage stimulation electrode hse1, and a second, optional, high voltage stimulation electrode hse2. Distal-most electrode lde may be part of a passive fixation assembly, known in the art, as illustrated, or part of an active fixation assembly, which is also known in the art, and stimulation electrodes hse1, hse2 may each be formed from tantalum or platinum coils that extend around an insulative body 130 of lead 100. Dashed lines in FIG. 1A represent elongate conductors 301, 302, 303, wherein a dot on each electrode represents an electrical coupling between each conductor 301-303 and a corresponding electrode lde, hse1, hse2; conductors 301-303 extend within lead body 130, through a connector transition zone 140 and into connector assembly 120. Lead body 130 and transition zone 140 are configured to electrically isolate conductors 301-303 from one another and may be formed from medical grade silicone and/or polyurethane. The coupling of each electrode lde, hse1, hse2 to the corresponding conductor 301, 302, 303 may be formed by any suitable method known in the art, for example, laser welding and/or crimping. FIG. 1A also shows a dot on connector pin 110 and on each of contact surfaces cs1-cs3 to represent an electrical coupling with the corresponding conductor 301-303.
According to FIG. 1A, conductor 301 couples distal-most electrode lde to connector pin 110, and conductor 302 couples stimulation electrode hse1 to both first and second contact surfaces cs1, cs2, such that lead 100 provides integrated bipolar pacing and sensing via electrodes lde and hse1, in addition to high voltage defibrillation stimulation via electrode hse1 (and electrode hse2, by the coupling to contact surface cs3, if electrode hse2 and the corresponding conductor 303 are included). Sealing surfaces ss1, ss2, ss3, ss4 are shown extending between connector pin 110 and contact surface cs1, between contact surfaces cs1 and cs2, between contact surfaces cs2 and cs3, and between contact surface cs3 and transition zone 140, respectively.
Those skilled in the art understand that pin 110 and contact surfaces cs1-cs3 are configured to mate with device contacts mounted within a connector receptacle of the device, and sealing surfaces ss1-ss4 are configured to mate with sealing rings, which are interspersed between the contacts within the device connector receptacle, so that an electrical coupling is made between each device contact and the corresponding pin/contact surface, within the receptacle, and these couplings are electrically isolated from one another by the sealing rings. According to the DF-4 standard, pin 110 and first contact surface cs1 are designated low voltage contacts, and second and third contact surfaces cs2, cs3 are designated high voltage contacts. The DF-4 standard also requires a specific configuration of terminal connector pin 110 and a uniform outer diameter D of connector assembly 120. If lead 100 does not include second stimulation electrode hse2 and corresponding conductor 303, the DF-4 standard still requires the presence of third contact surface cs3, albeit inactive, to preserve the standard form of connector assembly 120. According to FIG. 1A, first contact surface cs1 and second contact surface cs2 of exemplary lead 100 are electrically common with one another for the aforementioned integrated function of electrode hse1 (e.g., to function as a low voltage pace/sense electrode and as a high voltage stimulation electrode). However, with reference to FIG. 1B, if lead 100 is reconfigured to include another low voltage electrode for true bipolar pacing and sensing in conjunction with distal-most electrode lde, for example, a ring electrode le shown extending around lead body 130, just proximal to electrode lde, another conductor (not shown) extends within lead body 130, and electrically couples low voltage electrode le to first contact surface cs1. In this case, second conductor 302 is only electrically coupled to second contact surface cs2, and first and second contact surfaces cs1 and cs2 are not electrically common, being isolated from one another.
Although a variety of constructions for implantable medical electrical lead connector assemblies, which are similar to that described above, are known in the art, there is still a need for new constructions of lead connector assemblies that simplify the assembly process thereof to increase manufacturing efficiency and reduce cost.